He was the driving force in the revolutionary opposition to Charles I in the English Civil War, and was the leader of the Parliamentary forces (or Roundheads), winning decisive battles at Marston Moor and Naseby. After the trial and execution of Charles I, he returned to military command to suppress resistance to the Commonwealth in Ireland and Scotland, finally defeating a Scottish army at Worcester (1651) led by the future Charles II. With the establishment of the Protectorate, Cromwell became Lord Protector of the Commonwealth (1653–58); although he called and dissolved a succession of Parliaments, he refused Parliament’s offer of the crown in 1657. His rule was notable for its puritan reforms in the Church of England.